The Newtonian viscosity of the supercooled liquid measured by the continuous-strain-rate tensile test was investigated in the Pd_(40)Ni_(40)P_(20) metallic glass. It was found that continuous-strain-rate tests were applicable to determine the viscosity over a wide strain-rate region, and that the measured Newtonian viscosity η_(0) corresponded to the equilibrium one. The viscosity η over the entire strain-rate interval could be well described by one master curve expressed with a stretched exponential function η/η_(0)=1-exp(C/ε~(β)) in which β was 0.82. The free-volume-theory relation proposed by Cohen and Grest reproduced the equilibrium viscosity data over the entire temperature region better than the famous Vogel-Fulcher-Tammann relation. The supercooled liquid of the Pd_(40)Ni_(40)P_(20) metallic glass was classified into the relatively strong liquids as well as the other metallic glasses. The Pd_(40)Ni_(40)P_(20) metallic glass that is a metal-metalloid alloy exhibited to be more fragile than metal-metal glasses.
展开▼
